This application is based on and claims priority to Japanese Patent Application No. 2000-117400, filed Apr. 19, 2000 the entire contents of which is hereby expressly incorporated by reference.
1. Field of the Invention
This invention relates to a cooling system for a marine drive. More particularly, the present invention relates to a cooling system for a plurality of engine components of a marine drive.
2. Description of Related Art
Typically, an outboard motor comprises an engine disposed atop a drive unit of the motor. To propel the associated watercraft, the engine drives a propulsion device placed in a submerged position through a proper drive mechanism. The engine usually has an engine body and a plurality of components. The engine body normally comprises a cylinder block, a cylinder head assembly and a crankcase assembly. At least one combustion chamber, and often more than one combustion chamber, is provided within the engine. Other engine components can include, for example, an air intake system, an exhaust system, a fuel supply system, and an electric power generator.
The engine body and components usually generate heat during engine operations. The heat can accumulate in the engine body and associated components unless properly removed, and excessive heat can jeopardize normal engine operations. Typical engines thus have a cooling system that can cool the heated portions of the engine body.
One type of cooling system takes water from the body of water in which the outboard motor is being operated and guides the water through cooling jackets formed in the engine body. The cooling water draws heat away from the engine body before being discharged from the engine.
Two cycle internal combustion engines are often employed in outboard motors. Such two cycle engines are typically lubricated by supplying lubricant through the engine""s induction and porting system for lubricating the various moving components of the engine. Lubricant can be supplied in a wide variety of manners. For example, lubricant may be mixed with fuel, may be sprayed into the induction system of the engine, may be delivered directly to certain components of the engine, or may be supplied by any combination of the above.
In conventional two cycle engines, air from an air intake system travels through reed valves into a crankcase chamber of the engine. Air from the crankcase chamber then is supplied to the cylinders for combustion. Typically, fuel such as gasoline is mixed with lubrication oil and supplied to the air flow on an upstream side of the reed valves. The viscosity of this fuel/lubricant mixture is low in comparison with a typical lubricant alone. Because of its low viscosity, the mixture is easily sprayed and distributed to various parts of the engine for lubrication. The flow of the fuel/lubricant mixture across the reed valves also helps to cool the reed valves.
In order to reduce unburned hydrocarbons and engine exhaust emissions, and to increase engine performance, many internal combustion engines now employ direct fuel injection, wherein the fuel is directly injected into the cylinders. In these engine arrangements, the fuel is not mixed with lubricant. As a result, the viscosity of the lubricant is increased and consequently it is more difficult to deliver and distribute lubricant in the engine. Due to its high viscosity, lubricant particles tend to stick together during distribution. To avoid interference with the operation of the reed valves, the lubricant can be injected into the crankcase downstream of the reed valves and/or can be delivered directly to certain components. However, if lubricant does not flow across the reed valves, the reed valves may not be able to dissipate heat and may become excessively hot.
Accordingly, there is a need in the art for a two-cycle, fuel-injected engine having a cooling system that cools the engine intake system, as well as other engine components.
In accordance with one aspect, the present invention provides a marine drive comprising an internal combustion engine adapted to drive a propulsion unit. The engine comprises an engine body that at least partially encloses a crankshaft and has at least one combustion chamber. The engine further comprises an air intake system, a cooling system comprising a plurality of water jackets, and a flywheel generator. The cooling system has a coolant inlet and a coolant passage. The coolant passage delivers coolant to an intake system water jacket, which is arranged generally adjacent to the intake system, and to a combustion chamber water jacket, which is arranged generally adjacent to the at least one combustion chamber. The intake system water jacket and the combustion chamber water jackets are connected in parallel via the coolant passage so that water from one of the combustion chamber water jacket and intake system water jacket does not flow into the other of the combustion chamber water jacket and intake system water jacket. A generator water jacket is arranged adjacent at least a portion of the flywheel generator.
In accordance with another aspect of the invention, a marine drive comprises an internal combustion engine and a drive unit. The engine includes an engine body having a crankcase chamber, a substantially vertically oriented crankshaft at least partially enclosed within the crankcase chamber, a cooling system comprising a water jacket, a flywheel magneto generator, and an air intake system having at least one valve configured to selectively admit air into the crankcase chamber. The drive unit comprises a coolant inlet and a coolant passage. The coolant passage communicates coolant from the coolant inlet to the engine cooling system. The engine cooling system comprises an intake coolant jacket arranged adjacent the valve so as to direct a flow of coolant adjacent the valve, and a generator coolant jacket arranged adjacent at least a portion of the flywheel magneto generator so as to direct coolant adjacent the generator.
In accordance with yet another embodiment, the present invention provides a marine drive comprising an engine adapted to drive a propulsion device. The engine comprises a cylinder block defining at least one cylinder bore. A piston is arranged within the cylinder bore so as to reciprocate therein. A crankcase member defines, at least in part, a crankcase chamber at least partially enclosing a crankshaft and comprising an air guide portion having a valve for selectively allowing air to enter the crankcase chamber. A cylinder head is mounted onto the cylinder block. The cylinder head, cylinder bore and piston define a combustion chamber therebetween. A cooling system comprises a coolant supply passage configured so as to deliver coolant from a coolant source to an intake coolant jacket and to a cylinder head coolant jacket so that coolant is delivered to the intake coolant jacket independent of the cylinder head coolant jacket.
In accordance with a further embodiment, the present invention provides a marine drive comprising an internal combustion engine and a drive unit. The engine comprises an engine body at least partially enclosing a substantially vertically oriented crankshaft. The engine further comprises a flywheel magneto generator and a generator coolant jacket. The generator coolant jacket is positioned adjacent at least a portion of the generator. The drive unit comprises a coolant inlet and a coolant passage. The coolant passage communicates coolant from the coolant inlet to the generator coolant jacket.
In accordance with a still further embodiment, a marine drive comprises an internal combustion engine adapted to drive a propulsion unit. The engine comprises an engine body at least partially enclosing a crankshaft. A flywheel generator is mounted to the engine. Means for cooling the generator is positioned adjacent at least a portion of the generator.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiments which follows.